A. B. Pedersen, S. P. Johnsen, S. Overgaard, K. Søballe, H. T. Sørensen, and U. Lucht, “Regional variation in incidence of primary total hip arthroplasties and revisions in Denmark, 1996–2002”, ActaO, vol. 76, no. 6, pp. 815–822, Jan. 2005.